McGregor, Neil R, Armstrong, Christopher W, Lewis, Donald P et al. · Diagnostics (Basel, Switzerland) · 2019 · DOI
This study looked at what happens in the body during post-exertional malaise (PEM)—the exhaustion and worsening of symptoms that ME/CFS patients experience after physical or mental activity. Researchers measured chemical changes in blood and urine over 7 days in 35 ME/CFS patients who reported PEM and compared them to healthy controls. They found that during PEM, the body shows signs of increased metabolism (burning energy faster), low levels of a molecule called hypoxanthine, and problems with how cells use and process energy, along with evidence that the body is breaking down muscle protein.
Understanding the biochemical mechanisms of PEM is critical because it is the hallmark symptom of ME/CFS and the primary driver of patient disability. This study provides objective biological evidence of specific metabolic abnormalities during PEM, potentially opening pathways for diagnostic tests and targeted treatments that could help patients manage or prevent relapses.
This study demonstrates associations between biochemical changes and PEM severity but does not establish causation—whether hypoacetylation causes PEM or results from it remains unclear. The observational design cannot prove these metabolic changes are specific to ME/CFS or explain the underlying trigger of the hypermetabolic event. Findings require validation in larger cohorts and functional studies before translation to clinical practice.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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